This disclosure relates to detecting welded contactors in electric vehicles.
Generally, electric vehicles differ from conventional motor vehicles because electric vehicles are selectively driven using one or more battery-powered electric machines. Conventional motor vehicles, by contrast, rely exclusively on an internal combustion engine to drive the vehicle. Electric vehicles may use electric machines instead of, or in addition to, the internal combustion engine.
Example electric vehicles include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell vehicles, and battery electric vehicles (BEVs). A powertrain of an electric vehicle is typically equipped with a battery that stores electrical power for powering the electric machine. The battery may be charged prior to use. The battery may be recharged during a drive by regeneration braking or an internal combustion engine.
The powertrain of the electric vehicle includes contactors (or relays). During a drive cycle, the contactors close to electrically couple the battery with other areas of the powertrain. When the drive cycle is complete, the contactors open to, for example, protect a technician servicing the vehicle. If the contactor is welded closed, the contactor does not open and the circuit may remain open. Prior art techniques identify welds at key off at the completion of a drive cycle.